1. Field of the Invention
This invention relates to a method of manufacturing Hg.sub.1-x Cd.sub.x Te (also, hereinafter referred to as HgCdTe), and in more particular to a method of using a GaAs(211)B substrate and growing a CdTe buffer layer and a thin HgCdTe infrared detection layer on the substrate with high crystalline quality.
2. Description of the Prior Art
Formerly, when GaAs was used as a substrate material for a HgCdTe infrared detector, mainly the (100) plane and GaAs surfaces tilted slightly away from the (100) plane were used, and depending on the substrate heat treatment temperature and substrate heat treatment during exposure to a Te flux or Arsenic flux, a CdTe buffer layer was selected to be grown in the (100) or (111) orientation on the substrate, and a HgCdTe infrared detection layer was grown in either of these plane orientations on the substrates.
In the aforementioned method, during the high or elevated temperature heat treatment of the substrate, a problem exists in that the surface of the substrate becomes rough.
Also, it has been pointed out that if the thin HgCdTe film infrared detection layer was grown on the (100) oriented substrate, pyramid shaped protrusions were formed on the epilayer surface, and if the same layer was grown on the (111) oriented substrate, twinning occurred inside the crystal (refer to A. Million, L. DiCioccio, J. P. Gailliard and J. Piaguet, Journal of Vacuum Science and Technology A6 (4), Jul./Aug. (1988), 2813). These defects were a problem in that they lower the function of the HgCdTe infrared detection layer.
Furthermore, it has been reported that when a GaAs(211)B substrate was used as a substrate for a HgCdTe infrared detector, CdTe films were grown in both the (211) and (133) orientations on the GaAs(211)B substrates which were heat-treated at about 550.degree. C. and at a temperature lower by about 15.degree. C., respectively, while exposing the GaAs surfaces to a Te flux, and the CdTe growth temperatures were about 300.degree. C. (M. D. Lange et al., Appl. Phys. Lett. 58(18), 6 May 1991, pp. 1988-1990). However, it was difficult to selectively grow the CdTe film in either of the (211) and (133) orientations on the GaAs(211)B substrates with high crystalline quality.